Upon completion CORNWALL joined the China Station. In 1936 she returned from the Far East to the United Kingdom for a refit at Chatham which added more armour and a catapult and hangar for Walrus aircraft. In 1938 CORNWALL joined the 2nd Cruiser Squadron and in 1939 she once again transferred to the China Station, joining the 5th Cruiser Squadron.
In September 1939, after the outbreak of war, the cruiser moved to the Indian Ocean before operating in the central Atlantic, later returning to the Indian Oceanwhere she was sunk by Japanese carrier-based aircraft in April 1942